Spatio-temporal variation of fluid flow behavior along a fold: The Bóixols-Sant Corneli anticline (Southern Pyrenees) from UPb dating and structural, petrographic and geochemical constraints

Autor: Daniel Muñoz-López, David Cruset, Jaume Vergés, Irene Cantarero, Antonio Benedicto, Xavier Mangenot, Richard Albert, Axel Gerdes, Aratz Beranoaguirre, Anna Travé
Přispěvatelé: Ministerio de Ciencia, Innovación y Universidades (España), Generalitat de Catalunya, Ministerio de Economía y Competitividad (España), Vergés Masip, Jaume, Vergés Masip, Jaume [0000-0002-4467-5291]
Jazyk: angličtina
Rok vydání: 2022
Předmět:
Zdroj: Digital.CSIC. Repositorio Institucional del CSIC
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Popis: This study integrates field structural data, petrographic and geochemical (δ18O, δ13C, Δ47, 87Sr/86Sr, and elemental composition) analyses and U–Pb dating of calcite veins cutting the Bóixols-Sant Corneli anticline (Southern Pyrenees) in order to date and to investigate the spatio-temporal relationships between fluid flow and fold evolution. This E-W trending anticline grew from Late Cretaceous to Paleocene at the front of the Bóixols thrust sheet deforming pre-growth and growth sedimentary sequences. U–Pb dating reveals Late Cretaceous to late Miocene deformation ages, which agree with the age of growth strata deposition and the sequence of deformation interpreted from field and microstructural data. Dates coeval (71.2 ± 6.4 to 56.9 ± 1.4 Ma) and postdating (55.5 ± 1.2 to 27.4 ± 0.9 Ma) Upper Cretaceous to Paleocene growth strata are interpreted to record: (i) the growth of the Bóixols-Sant Corneli anticline during the Bóixols thrust emplacement, and (ii) the tightening of the anticline during the southern tectonic transport of the South-Central Pyrenean Unit. Other ages (20.8 ± 1.2 to 9.0 ± 4.6 Ma) postdate the folding event and have been associated with the collapse of the Bóixols-Sant Corneli anticline. The geochemistry of calcite veins indicates that the fluid flow behavior varied across the Bóixols-Sant Corneli anticline through its growth, showing a compartmentalized fluid system. In the hinge of the anticline and in the upper Santonian to middle Campanian syn-orogenic sequence along the footwall of the Bóixols thrust, the similar petrographic and geochemical features between all calcite cements and host rocks point towards a locally-derived or well-equilibrated fluid system. Contrarily, along large faults such as the Bóixols thrust, and in the anticline limbs, the geochemistry of vein cements indicates a different scenario. Cements in large faults yielded the lightest δ18O values, from −8 to −14 ‰VPDB, and variable enrichment in δ13C, 87Sr/86Sr, elemental composition and δ18Ofluid. This is interpreted as the migration of fluids, through fault zones, that evolved from distinct fluid origins. Cements in the fold limbs exhibit δ18O and δ13C between −8 and −6 ‰VPDB and between −10 and + 2 ‰VPDB, respectively, the lowest Sr contents and the lowest precipitation temperatures, suggesting that the anticline limbs recorded the infiltration and evolution of meteoric waters. The paleohydrological system in the Bóixols-Sant Corneli anticline was restricted to the Bóixols thrust sheet. The Upper Triassic evaporitic basal detachment likely acted as a lower fluid barrier, preventing the input of fluids from deeper parts of the Pyrenean crustal thrust system. This study provides a well-constrained absolute timing of fracturing and fluid flow during basin inversion and folding evolution and highlights the suitability of U–Pb geochronology to refine the age of fractures and veins and their sequential evolution in orogenic belts.
This research was carried out within the framework of the DGICYT Spanish project PGC2018-093903- B-C22 (Ministerio de Ciencia, Innovaci´on y Universidades/Agencia Estatal de Investigación/10.13039/501100011033/Fondo Europeo de Desarrollo Regional, Uni´on Europea), the Grup Consolidat de Recerca “Geologia Sediment`aria” (2017-SGR-824) and the Grup Consolidat de Recerca “Modelitzaci´o Geodin`amica de la Litosfera” (2017SGR-847). This work was also partially funded by ALORBE project (PIE–CSIC–202030E310). The PhD research of DML is supported by the FPI2016 (BES-2016-077214) Spanish program from MINECO. DC acknowledges the Spanish Ministry of Science and Innovation for the “Juan de la Cierva Formaci´on” fellowship FJC2020-043488-I AEI/ 10.113039/501100011033. We thank Luis Fernando Martínez for helping in the fieldwork during his master’s degree at the Universitat de Barcelona. Carbon and oxygen isotopic analyses were carried out at the Centre Científics i Tecnol`ogics of the Universitat de Barcelona. Strontium analyses were performed at the CAI de Geocronología y Geoquímica Isot´opica of the Universidad Complutense de Madrid. The elemental composition was analyzed at the geochemistry facility labGEOTOP of Geosciences Barcelona (GEO3BCN–CSIC). U–Pb analyses were performed at the Frankfurt Isotope and Element Research Center (FIERCE) from the Goethe-University Frankfurt (Germany).
Databáze: OpenAIRE
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